Handling Animated Distortion on a Shot with Zoom

Shows how SynthEyes's lens parameter solving modes can be used to determine animated lens distortion parameters on a shot with a large zoom. "Animate on keys" mode allows a tailored distortion curve, preventing the animated distortion parameters from introducing jitter into the solved shot.

Script for Search Engines:

Hey, this is Russ Andersson. In this tutorial, I'm going to show some animated distortion handling using SynthEyes and the new capabilities in the solver. So I've got a really old shot here. This is an outtake from a helicopter shoot a long time ago. It's actually standard definition footage, of all things, but it serves our purpose here, so let's give it a whirl. We're just going to start out by jacking up the number of trackers, so we have plenty to keep track of what's happening, and we don't have to really mess with them a whole lot. So run those out and just set this thing up as a zoom shot, and there's our initial solve. Okay, so great now. This is a older camcorder-style camera and with a built-in zoom and those things tend to have a bit of distortion when they're opened up wide, and then as you zoom in the distortion is less. So we want to take a look at that, and to do that we're going to switch to the radial plus squash lens model, which is just kind of an updated version of the original SynthEyes lens model, but this supports the newer features for different solving modes. So I'm just sequencing through these by left clicking, and I can go in reverse by right clicking. So let's just calculate the quadratic coefficient on every frame, and we'll switch to a Refine to let that happen. There we go. Now we'll go over to the graph editor. Let's take a look at what we've got. I'm going to turn on the field of view. Let's turn off all the other stuff. And now we can look at this distortion as well. And what you notice is that this distortion curve is a lot jitterier than the field of view curve. And that's true and if you think about it, there's a lot more information required to figure out what's uh what the distortion is. It just it just winds up being a jitterier thing, and as you have additional distortion coefficients as well, then there's even more potential for jitter. So that can wind up showing up in our final path and in the output as well. This isn't terrible by any means. It can get bad. So the question is, what do we do about that? Filtering isn't really the right approach a lot of times. Especially when they're rapid transitions like this, if you try and filter something out then you're throwing away what happens in that boundary a lot, and creating some pretty bad sliding in those particular locations. So in this version of SynthEyes, there's an additional option of switching to "animated keys" mode where it's gonna interpolate between the keys that you have. So I'm going to just start deleting a bunch of these keys from that distortion value, and I just turn off the field of view so I don't take anything out on that. So let's just take out a bunch more of them, and we'll leave a couple and here we go. Now we've got a bunch of values. Now those are just the ones we had but taking away the other ones. But now because of this "animated keys" mode, when I run the solver now, it goes and computes the best locations for those key values, taking into account all these other frames also. So it's kind of averaged out, so that the slope of this best matches. So this value is not just for that particular frame, but the best value to put here to make all these other frames well too. And same for the ones at the end. So this gives you a much smoother curve for this distortion, while still kind of giving you the best results that you can get for what the degree of change that you've allowed. So now if I need to, if I want to see what's happening in some more detail. If there's a little more detail that I want around the transitions, I can add some keys back in, and just pop over to the solver again, and have it start working out what's happening, to again keep those values as best they can be. So this is a really important mode, this "animated keys," and I expect that that's going to be what you deliver in a solve and a completed track. That "animated frame" mode is good for figuring out where things are happening in the first place, if you're able to use it. And in a bad situation, when there aren't all that many trackers at all, you may not even be able to use this "animate by frame" mode without just trashing the entire solution. So in that case, you might just eyeball the scene and try and decide where a rack focus starts and ends, and use that to decide where you put your keys at. There's also a script around that lets you put distortion keys down every couple of frames throughout a shot, and that will allow you to get a rough initial solution and then be able to adjust it some more subsequently. So I hope this gives you a quick idea of the sort of thing you could do. Obviously, you can play around with this plenty more. Thanks, hope it helps, and have a good day.